Bayes-Turchin approach to x-ray absorption fine structure data analysis

Abstract

X-ray absorption fine structure (XAFS) data from copper, gold, and germanium are analyzed in the framework of the model-independent Bayes-Turchin approach. Compared to earlier treatments, we also obtain spring constants, besides shell radii, Debye-Waller (DW) parameters, and anharmonicity parameters. The use of spring constants instead of DW parameters reduces considerably the number of model parameters needed to achieve a satisfactory fit of the data. The ab initio extended XAFS code FEFF7 is used in the analysis. The various sources of uncertainty in the input data and in the FEFF7 code are carefully assessed and used in the analysis. It is shown to which degree the model parameters are determined by the data, rather than by the a priori assumptions. A posteriori errors and error correlations between model parameters are shown.